German Patent document DE-OS-44 09 033 discloses a pilot valve having an intermediate rod that is inserted between the magnet armature and the valve plate and is radially guided in the valve housing within longitudinal ribs. The valve plate is radially and axially supported in a ball-socket bearing, the intermediate rod abutting against the magnet armature without radial support. The pilot valve is used particularly in internal combustion engines, for example, in a ventilation device for a fuel tank or as a shutoff valve in a crankcase in a ventilation system.
Such valves are used under harsh conditions, such as in motor vehicles under conditions of air containing dust or oil. As shutoff valves, they must meet high demands with regard to impermeability over a long lifetime, while being maintenance-free. Furthermore, manufacturing this mass-produced product economically must be possible.
Known designs typically include many parts and a complicated geometry. Furthermore, there is the danger that dirt particles can get into the armature guide-region of the magnet armature.
The object of the present invention is to offer better protection against the penetration of dirt particles into the sensitive armature guide-region, while maintaining a simple design with a simple assembly.